We propose the NanoSystems Biology Cancer Center (NSBCC) as a collaboration between Caltech and the UCLA Geffen School of Medicine, to develop nanotechnologies for addressing challenges in combinatorial cancer therapies. Four scientific Projects are supported by two Core Resources and an Administrative structure designed to promote cross-university interactions at the frontiers of cancer biology, clinical oncology, and the basic and engineering sciences. By leveraging strong support from our respective institutions, the Jonsson Comprehensive Cancer Center, and commercial partners, we integrate world-class physical, biological and engineering sciences at Caltech with cutting edge cancer biology and cancer clinical care at UCLA. The NSBCC faculty include four clinical researchers, 5 assistant professors, and several senior researchers from both campuses, and is led by led by Jim Heath (Caltech) and co-led by Michael Phelps (UCLA). Heath and Phelps have track records of building leading cancer research programs that draw across disciplines, with effective translation into the clinic and marketplace. Our Projects balance discovery with translation. Two Projects involve nanotherapies, and two involve the development of nanotech tools for guiding the selection of combination both cancer immunotherapy and targeted therapy treatments. We focus on brain cancers and melanoma, which allows us to take advantage of momentum from the current funding cycle. However, we seek broadly applicable technologies. This holds especially for the case of immunotherapy, where the challenge is to bring the remarkable recent successes in the field (partly driven by our investigator's melanoma trials) to larger patient populations. In Proj. 1, we propose nanoparticle (NP) vehicles designed to deliver therapies and therapy combinations to fully engage a tumor that lies across an intact blood brain barrier (BBB). This project builds upon initial promising results, and from an NSBCC history of delivering NP therapeutics into Phase I and Phase II (and soon Phase III) trials. Proj. 1 takes guidance (as well as a novel panel of human-derived intracranial tumor models) from Proj. 4, where we propose nanotech and microtech tools to quantitatively assay for >200 proteins and metabolites from single cancer cells separated from a GBM tumor, with the goal of understanding the dynamical responses of those cells to targeted monotherapies. Those responses invariably lead to some form of resistance, and we seek to decode those responses to identify effective therapy combinations. For Project 2 we propose to integrate 3 Caltech inventions. The first are epitope targeted PCC Agents (Heath), which are synthetic ligands that can be developed to target oncoproteins containing single activating point mutations. We target the oncoproteins AktE17K and KrasG12D. KrasG12D is the most dominant oncoprotein in human cancer, and also considered undruggable. These targeting ligands are combined with proteolysis-targeting chimeric molecules (protacs; Deshaies) that exploit the natural cellular machinery to label a protein for destruction. The PCC Agent-protacs are delivered into cells by adapting NP chemistries that were first developed and clinically translated by Davis. Targeting just the mutant protein can open up the therapeutic window for targeted inhibitors, thus enabling new therapy combinations. In Project 3, we turn to cancer immunotherapy by evolving our powerful suite of immune monitoring tools into platforms for understanding immune cell/tumor cell interactions within the tumor microenvironment. In particular, guided by exome analysis of the tumor, we construct nanotechnology-based libraries for a ~60-plex sorting of tumor neoantigen specific T cell populations that can be applied directly to fresh biopsied tumors. This helps identify those T cells that have clonally expande within the tumor, and permits us to identify the tumor antigen, the T Cell receptor ?/? sequence (for cloning), and the functional activity of the T cell. This technology is applied a set of matched patient tumor biopsies from recent immunotherapy trials run by Project 3 PI Ribas, and should provide guidance for treating those patient groups that currently exhibit transient, positive responses to PD-1 blockade, as well as helping to frame treatment ideas for patients that do not exhibit even transient responses. In Project 3, we also propose a novel in vivo imaging nanotechnology for the kinetic tracking of T cell infusions in tumor models. The technology draws from the genetic ability of certain microorganisms to generate gas- filled nanovesicles, and yields an image contrast mechanism that will be adapted to TCR- or chimeric antigen receptor (CAR)-engineered T cells for imaging T cell infiltrates into mouse tumor models, using the high resolution imaging modalities of ultrasound or hyperpolarized 129Xe MRI. This provides us with the ability to test, in vivo, hypotheses generated from the in vitro assays. For all projects, significant preliminary data is provided.